<!DOCTYPE html>
<html>

<head lang="en">
    <meta charset="UTF-8">
    <title></title>
    <style>
        .login-header {
            width: 100%;
            text-align: center;
            height: 30px;
            font-size: 24px;
            line-height: 30px;
        }

        ul,
        li,
        ol,
        dl,
        dt,
        dd,
        div,
        p,
        span,
        h1,
        h2,
        h3,
        h4,
        h5,
        h6,
        a {
            padding: 0px;
            margin: 0px;
        }

        .login {
            width: 512px;
            position: absolute;
            border: #ebebeb solid 1px;
            height: 280px;
            left: 50%;
            right: 50%;
            background: #ffffff;
            box-shadow: 0px 0px 20px #ddd;
            z-index: 9999;
            margin-left: -256px;
            margin-top: 140px;
            display: none;
            
            /* 不让文字被选中 */
            -webkit-user-select: none;
            -moz-user-select: none;
            -ms-user-select: none;
            user-select: none;
        }

        .login-title {
            width: 100%;
            margin: 10px 0px 0px 0px;
            text-align: center;
            line-height: 40px;
            height: 40px;
            font-size: 18px;
            /* position: relative; */
            cursor: move;
            -moz-user-select: none;
            /*火狐*/
            -webkit-user-select: none;
            /*webkit浏览器*/
            -ms-user-select: none;
            /*IE10*/
            -khtml-user-select: none;
            /*早期浏览器*/
            user-select: none;
        }

        .login-input-content {
            margin-top: 20px;
        }

        .login-button {
            width: 50%;
            margin: 30px auto 0px auto;
            line-height: 40px;
            font-size: 14px;
            border: #ebebeb 1px solid;
            text-align: center;
        }

        .login-bg {
            width: 100%;
            height: 100%;
            position: fixed;
            top: 0px;
            left: 0px;
            background: #000000;
            filter: alpha(opacity=30);
            -moz-opacity: 0.3;
            -khtml-opacity: 0.3;
            opacity: 0.3;
            display: none;
        }

        a {
            text-decoration: none;
            color: #000000;
        }

        .login-button a {
            display: block;
        }

        .login-input input.list-input {
            float: left;
            line-height: 35px;
            height: 35px;
            width: 350px;
            border: #ebebeb 1px solid;
            text-indent: 5px;
        }

        .login-input {
            overflow: hidden;
            margin: 0px 0px 20px 0px;
        }

        .login-input label {
            float: left;
            width: 90px;
            padding-right: 10px;
            text-align: right;
            line-height: 35px;
            height: 35px;
            font-size: 14px;
        }

        .login-title span {
            position: absolute;
            font-size: 12px;
            right: -20px;
            top: -30px;
            background: #ffffff;
            border: #ebebeb solid 1px;
            width: 40px;
            height: 40px;
            border-radius: 20px;
        }
    </style>
</head>

<body>
    <div class="login-header"><a id="link" href="javascript:void(0);">点击，弹出登录框</a></div>
    <div id="login" class="login">
        <div id="title" class="login-title">登录会员
            <span><a id="closeBtn" href="javascript:void(0);" class="close-login">关闭</a></span>
        </div>
        <div class="login-input-content">
            <div class="login-input">
                <label>用户名：</label>
                <input type="text" placeholder="请输入用户名" name="info[username]" id="username" class="list-input">
            </div>
            <div class="login-input">
                <label>登录密码：</label>
                <input type="password" placeholder="请输入登录密码" name="info[password]" id="password" class="list-input">
            </div>
        </div>
        <div id="loginBtn" class="login-button"><a href="javascript:void(0);" id="login-button-submit">登录会员</a></div>
    </div>
    <!-- 遮盖层 -->
    <div id="bg" class="login-bg"></div>
    <script>
        // 获取元素
        var link = document.getElementById("link");
        var login = document.getElementById("login");
        var bg = document.getElementById("bg");
        var closeBtn = document.getElementById("closeBtn");

        // 点击link 弹出登录框和背景颜色遮盖
        link.onclick = function(){
            login.style.display = "block";
            bg.style.display = "block";
        }
        // 点击关闭 弹出登录框和背景颜色遮盖
        closeBtn.onclick = function(){
            login.style.display = "none";
            bg.style.display = "none";
        }

// 拖拽登录框
        // 鼠标按下登录大盒子时
        title.onmousedown = function(e){
            // 可以确定鼠标点击位置的距离html页面左上角的位置 e.pageX e.pageY
            // 可以确定大盒子据距离html的偏移位置 login.offsetLeft/login.offsetTop
            // 因此确定 鼠标点击时的位置:距离大盒子内部的水平距离及垂直距离
            e = e || window.event;
            var l = e.pageX - login.offsetLeft;
            var t = e.pageY - login.offsetTop;
        // 鼠标移动时 大盒子随着移动
            title.onmousemove = function(e){
                // 鼠标点击时的位置不变 :l 和 t 的不变化
                // 可以确定鼠标移动后的位置的距离html页面左上角的位置 e.pageX e.pageY
                // 因此确定移动后的大盒子据距离html的偏移位置 login.offsetLeft/login.offsetTop
                e = e || window.event;
                var newleft = e.pageX - l;
                var newtop = e.pageY - t;
                login.style.left = newleft + "px";
                login.style.top = newtop + "px";
            }
        }
        // 鼠标按键放开时 大盒子不再移动
        title.onmouseup= function(){ 
            title.onmousemove = null;
        }

    </script>
</body>

</html>